LISBON (AFP) - European and IMF officials kick off tough talks Monday with Portuguese authorities on the scale and the modalities of a massive international bailout expected to involve scores of billions of euros. The negotiations on the sum and payback conditions follow an evaluation mission last week to Lisbon by the European Commission, the European Central Bank and the International Monetary Fund. Portugal goes to early polls on June 5. The government of Prime Minister Jose Socrates government fell last month when parliament rejected its latest austerity plan, forcing Lisbon to bow to market pressure and seek an EU-IMF bailout. The talks are supposed to agree a programme of tough austerity measures by mid-May for the political parties to agree on before the polls take place. European Commission head Jose Manuel Barroso, a former Portuguese prime minister, has stressed that European Union and IMF aid, expected to total 80 billion euros ($116 billion), will be a medium-term programme with strict conditions. The negotiations could last a week, a spokesman for the European Commission in Portugal told AFP. The European Commission delegation will be headed by German Juergen Kroeger while his compatriot Rasmus Rueffer will lead the European Central Bank team. The IMF side will be headed by Dane Poul Thomsen, who was involved in the Greek bailout package a year ago while the Portuguese team will be co-headed by Finance Minister Fernando Teixeira dos Santos and Pedro Silva Pereira, the spokesman of the caretaker goverment. The EU and the IMF have each warned that Lisbon will have to implement more public spending cuts, tax rises and far-reaching privatisation to secure its lifeline. On Tuesday, the visiting teams will hold talks with employers associations and labour unions. The debt rescue, finally agreed to after months of agonising efforts to avoid having to call for help, is hugely controversial in Portugal where many view it as a national humiliation.